Telephone system.



A. R. KAHL. TELEPHONE SYSTEM. APPLICATION FILED JULY 16, 1907.

Patented Sept. 5, 1911.

2 SHEETSSHEET 1.

INVE NTQR WITNESSES fl T 2% A. R. KAHL. TELEPHONE SYSTEM.

I APPLICATION TILED JULY 16, 1907. 1,0,QTZ.

Patented Sept. 5,1911.

2 SHEETS-SHEET 2.

FIGURE-3 FIGURE-4 J1 L9 77 67 67 To all whom'it may concern:

run STATES FATE ARTHUR, B. KAHL, DIE ROCHESTER, NEW YORK, ASSIGNOR .IIO STROMBERG-GABLSON TELEPHONIfMANUFACTUBING COMPANY, OFiBOGHES'I'ER, NEW YORK BATION or NEW'YORK.

In operating automatic telephone systems,

the common practice is to employ metallic circuits and to send impulses from one end of the line, usually the subscribers station,

to the automatic a paratus located at the exchange, first over one line conductor for operating one part of the automatic -apparatus, and then over the other conductor for establishing a relation for selecting the required condition on the next apparatus, which selection is accomplished by again sending impulses over the first, conductor, and so on, these impulses effecting a selection at the central oliice of. the connection desired by the -calling subscriber. At the close of the conversation, by means of replacing the receiver on the hook switch, impulses are sent over one or both line conductors simultaneously according to thcsystem used, which im u1 ses operate appara-.

tus at the central exc ange for clearing out and returning to normal condition all of the selecting apparatus that has been previously operated. The apparatus-employed in automatic exchange work, on account of the me chanical work it necessarily does, is usually of comparatively heavy construction, and is therefore not as sensitive or rapid in its:

operation as apparatus commonly employed in manual exchange work. It'is often necessary to connect by means of trunk lines from a manual telephone exchange to an automatic exchange, and in the trunk circuit thus used it is desirable to provide for restoring the automatic apparatus, by the mere act of taking down the connection at the manual exchange to said trunk line. In the past this result has been accomplished by using a multiplicity of ordinary electromagnetic mechanisms, or by the use of auxiliary mechanical dev ces, the result in either TELEPHONE SYSTEM.

Specification of Letters I'atent.

Application filed July 16, 1907. Serial No. 384,087.

A CQBPO'.

Patented Sept. a, 1911.

case being to give a sufficient length of impulse on disconnecting from such trunk line to positively release and restore to its normal condition the automatic apparatus previously operated to make connection with the desired automatic exchange subscriber.

It is the object of my invention to make use in a trunk connection of the character described, of ordinary electro-magnetic telephonic relays, and to reduce the number of these devices to a minimum without reduc- .ing the length of impulse imparted to the conductors extending to the automatic apparatus, when the connection with the trunk line is taken down. I

It is also an' object of my invention to eliminate any and all auxiliary mechanical devices that have heretofore been used in this connection to effect the properlength of releasing impulses. p

It is a further object of any invention to produce an electro-magnetic device capable of use in electrical systems generally which shall be so arranged and connected as to have a natural rate of deenergization of longer time interval relatively than the time interval required for the energi zation of such device, without in any way impairing the sensitiveness or speed of energization of such device. 1

The several drawings illustrating my. in-

vention are as follows:

Figure 1 shows in diagrammatic view all of the electrical connectionsand apparatus essential to the operation of my invention.

Fig. 2 shows in somewhat more'diagrammatic view the complete connection between a subscriber to the manual exchange and a subscriber to the automatic exchange when connection is properly established for con} versation. Figs. 3 and 4 are detailed views showing particular embodiments of my-invention which will be explained'later.

Similar letters refer to similar parts throughout the several views.

Referring to. Fig. 1, when a subscriber to the manual exchange desires connection he removes his receiver 5 from the hook switch 2 thereby .closing a circuit through such hook switch and primary winding of his induction coil as follows: grounded side of battery B, Wire 17, non-inductive winding n of'line relay 1' contact 13, line wire 8, transmitter 1, primary Winding 3, hook switch 2, line wire 9, contact 14, energizing winding of line relay 1' wire l6,'back to battery B. This energizes line relay 1" and closes a circuit as follows: grounded side of battery B, wire 17, contact 15, line lamp a, wire 16,

5 back to battery B and thus the signal lamp a is lighted, indicating to the operator that the subscriber corresponding thereto desires connection. The operator thereupon inserts plug. p in answering jack j, the tip 20 and sleeve 21 of such plug making contact respectively with tip and sleeve springs and 11. Sleeve 21 of the plug 1 makes contact at the same time with ring 12 of the answering jack, closing a circuit as follows: grounded side of battery B, wire 17, winding of cut-off relay 1', ring '12, sleeve 21, contact 27, winding of sleeve relay r wire 47, back to battery B. Thus the cut oif relay 7 is energized and connection with battery B is cut off from the line' wires 8 and 9 at contacts 13 and 14 respectively. Sleeve relay 7* is also operated at this time closing contact 19 for afpurpose to be described later. Tip supervisory relay r is also energized at this time, current taking the following path: grounded side of battery B, wire 46, winding of tip supervisory relay 1, contact 30, contact 26, tip 20, spring 10, line wire 8, transmitter 1, primary winding 3,

0 hook switch 2, line wire 9-, spring 11, sleeve 21, contact 27, winding of relay 7 wire 47,

back to battery B. Thus both relays r and r are energized which maintains contact 18 open and prevents the supervisory lamp a from lighting.

The relays r and r have armatures extending longitudinally thereof and substantially parallel with, their cores. These armatures are arranged adjacent to each other,

as indicated in the drawings, and are separated by a block of suitable material attached to one of them. As a result, when the armature of the relay 1" is attracted the contact 19 is closed and the armature of the relay 7* is permitted to drop to a position closing the contact 18. With the relay r still energized, if the relay 1' is energized, its armature is attracted, thereby serving to open the contact 18. When the relay 1 is deenergized, whether therelay 1' is energized or not, the retracting spring attached to the armature of the relay 7* serves to move it to its unattracted position and serves to move, as a result of the connections described, the armature of the relay r to the position it would assume if attracted, as a resultof which the contact 18 is opened.

n1 order to ascertain the connection de- 29, contact 27, sleeve 21 of plug p, which places the operators receiver in circuit with the callingsubscriber; The operators talking circuit is as follows: battery 13*, transmitter 41, primary winding 42,;back to battery B Thus the operator ascertains the connection desired and on learning that the calling subscriber desires to communicate with a subscriber connected to the automatic exchange, plugs into one of the trunk jacks j with the plug 10 if the trunk connected with such jack is idle, which fact is indicated by the condition of the busy lamps a associated with themultiple jacks 7' connected to such trunk line. For such position of the plug 9 tip22 and sleeve 23 make contact respectively with tip and sleeve springs 49 and 50 by the spreading of which, contact 51 is closed and a circuit is established as follows: grounded side of battery 35 B, wire 46, wire 48, contact 51, windin of relay 1*, resistance 1?, wire 47, back to attery B. Thus relay 0 is energized and contacts 52 and 53 are made and contacts 54, 55 and 56 are broken. The closing of contact 52 completes a circuit as follows: groundedside of battery B, contact 52, wire 7 3, through the busy lamps a, a in parallel, wire 74, wire 47, back to battery B. Thus busy lamps a? are lighted indicating that this particular. trunk is busy. The opening of contacts 55 and 56 cuts off drop d from the conductors 67 and 68. The functions performed by the other contacts operated by relay T will be explained later. The oper-- ator at the manual exchange now throws key M so as to open circuit the cord and connect the selecting keys is and 7a to the sleeve and tip 23 and 22 respectively. The operator now sendsthe proper number of impulses by one of these keys as k which by closing contact 39 establishes the following circuit:

from the grounded side of battery B ground G ground G, wire 46, contact 39, contact 34, tip 22, spring 49, wire 67, winding of the relay 1' contact 66, contact 65, back to battery B. This relay 1" is the relay that is adapted to operate the first or vertical magnet of the first selector switch of the automatic mechanism; this magnet is not shown and neither are any of the mechanical parts connected with the automatic exchange indicated since these parts are well understood in the art and form no part of this invention; only such parts of the automatic exchange are indicated in. connection with this drawing and specification as are essential to the description of this particular invention, which does not consist' in operating an automatic exchange but does, in this embodiment, consist. in effecting the operation of the so-called re-'- lease magnet of such exchange, which magnet is well known in the art and'p'erforms functions which are also well known; thereand k thefirst' selector, any number of selectors fore its energization and deenergization is believed to be sufficient to indicate the restoration of the mechanism of the automatic exchange to itsinitial condition after having been operated. Similarly the other relays indicated as a part of the automatic exchange apparatus may perform other functions additional to those indicated on .this drawing and in this specification without necessitating a description of such'apparatus and operations, since they form no part of this invention, and since the functions of all of these relays are well known in the art and call for'no explanation. Thus it will be seen that the operation of the relay r serves to operate the first automatic selector switch in one direction, usually vertically, as desired, according to the number of impulses sent by the key When the desired position in this direction is reached, key 70 is depressed closing contact 38 and establishing a circuit as follows: grounded side of battery B ground G, ground G, wire 46, contact 38, contact 35, sleeve 23, spring 50, wire 68, winding of relay 1*, contact 65, back to battery B Thus relay 7* which is known as the rotary relay, is operated and this relay, as is well known, besides closing contact 64 operates to move the first selector in a second direction, usually a motion ofrotation, which-continues until a connection to the proper second selector switch is secured. By the operation of the first selector switch just described, wipers 98and 99 are moved into cont-act with those contacts tion trunk conductors 67 and 68 are con nected'by wires 112and 111 with wipers 98 and 99 and thus to wires.96 and 97' and since these wires 96 and 97 lead to; the vertical and rotary relays respectively of the second selector switch, such secondselector maynow be operated by, means of keys 70. In the manner-just described ,for

may be successively operated according to the size of, the automatic exchange and finally the particular connector switch at which the desired subscribers line terminates is similarly operated and'talking connection is established' between the calling and calledsubscribers as follows: winding bof thc repeating coil, condenser 32, winding Z, contact 27, sleeve21 of plug ,1), spring 11, line wire 9, hook switch- 2, primary winding transmit-ter 1 line wire 8, spring 10, tip 0, plug 72, contact 26, contact 30, to repeating coil 6. The other side of this repeatingcoil is connected as follows: winding 6 condenser 33, winding 6 contact 37,

sleeve 23, spring 50, trunk conductor 68, switch 94, wire 111, wiper 99, conductor 97, to and through the selector switches and connector switch and thus to the called subscriber, back to conductor 96, wiper 98, wire 112, switch 95, trunk conductor 67, spring 49, tip 22 of plug 9 contact 36,- to winding 6 thus the two subscribers are connected inductively through the windings b and 7) of the repeating coil in the cord circuit. Current is supplied to the subscriber connected with the manual exchange by the circuits already traced through relay windings 1" and r from battery B. In the modificat-ion shown in Fig; 1 the subscriber connected with the automatic exchange is as sumed to have local battery apparatus and hence no battery connection is made to the automaticv end of the cord circuit indicated. I

Should the operator move her key k to the listening position during a conversation to determine whether the connection is in use, provision is made to prevent opening the talking circuit which would otherwise occur at contact 30, by the closure of contact 19 by the operation of relay r thus establishing" a second electrical path from tip 20 through contacts 26 and 19 to winding b.-

When the subscribers have finished conversing, the operator at the manual exr ch nge is informed of the fact by the man ual subscriber replacing receiver 5 on hook switch 2 thus breaking contact between primary winding 3 and such hook switch and opening the circuit through tip supervisory relay 1'. Thus'contact 18 is closed and supervisory lamp a is lighted, current taking the following path: grounded side of battery B, wire 46, contact 18, lamp (1 wire 16, back to battery B. In response to this signal the operator withdraws the plug 79 from the answering jack j, which opens the energizing circuit of relay '7', permitting the contacts 13 and 14 to be closed, for which condition relayr remains deenergized since the energizing circuit is broken at .hook switch 2 and thus the line apparatus connected with the manual exchange subscriber is restored to its normal condition. The operator also withdraws the plug p from the multiple jack j which first results in opening contact 51. This does not, however, permit the relay r to become deenergized since a second energizing path is established to battery B as follows:'grounded side of battery-B, winding of relay r contact 53, windbattery B, and thus relay 1' is energized and contacts 57 58, 59'and 60 are closed. Attention is.called to the fact that this relay r was not operated during the time that the plug p 'was in the jack 7' for the reason that both terminals of its energizing winding were connected with the grounded side-ofhattery B, one terminal being connected directly with such terminal of the battery. while the other terminal was connected through contact 53, wire 75, contact 51, wire 48 and wire 4-6; immediately on closing contacts 59 and 60, conneqtion 'is established between ground G and trunk conductors 67 and 68 as follows: ground G contacts 59 and 60, wires 69 and 70 to trunk conductors 68 and 67 respectively; thus relays 1- and r as well as the similar relays of the other selector and connector switches operated, are energized as thelr windings are connected 'with wires 67 and 68, the other terminals being connected through contacts 65 and 66 with the sleeve or live side ol battery B These relays remain energized as long as this grounded. condition of the trunk conductors 67 and 68 is maintained. The ener ization of the relay 1' closes contact 64 and estabing winding of magnet 1"", back to battery energized in a manner similar B. Thus magnet 7*, which is known as the.

release magnet, is energized, which condit1on 1s maintained as long as wires 69 and are grounded by the operation of relay 7' Since the apparatus used in automaticex changes is generally of relatively heavy construction, and since a number of selector switches are usually operated in effecting a connection, it is necessary that the release magnet 1" be energized for a considerable time interval relatively, to permit the mechanism operated to return to its initial posi: tion, which is secured by the arrangement of the circuits used to deenergize relays --r and 1'. \Vhen the relay '1' is energized by closing cont-acts 57 and 58 an external electrical path of low resistance is established between the terminals of the energizing winding of relay '2', which results in the deenergizat-ion of such relay 1' but at a rate much slower than its normal rate of energization due to the fact that a. comparatively good path .is provided tor'the flow of current induced by' the gradually decreasing magnetic flux through the energizing winding of such relay r*, which reacts upon such relay and tends to maintain its energizedcondition. When this relay is finally deenerg'ized it opens contact '52 and thereby extinguishes lamps a, (L2 and also opens contact -53 and closes contacts 54, 55 and'56. By closing contact 54 an external electrical path of low resistance is established bet-ween the terminals of the energizihgwinding of relay r as a result of'which siich f elay is deto that just and At the same time this connection described for relay W, and when such relay r is: completely denergized contacts 57, 58, 59 and 60 are opened, thus removing the ground from the trunk conductors 67 and 68. Thus it will be seen that by utilizing the reactive effect of the self induction of the windings of relays r and 1- a considerable time interval is secured between the energization of relay 9" (and the simultaneous grounding of the trunk conductors 67 and 68) and the deenergi'zation of such relay, although such deenergization is a direct result of the act that energized it, and as a result the magnet r is energized for a corresponding interval, such interval being of sufficient length to permit the complete restoration ofthe apparatus at the automatic exchange to its initial condition, and this interval may be made of suitable length by modifications indicated in connection with Figs. 3 and 4.- if an interval difi'erent from that secured by the showing of Fig. 1 is necessary. The contact 57 is provided in connection with relay 9' for the purpose of maintaining such relay 7" energized while the armature of relay? is falling away 'from contact 53 and making contact 54, the

as follows: grounded terminal of battery B,

winding 7' contact 57 contact 58, resistance 1?, back to battery B. This provides that the relay r shall not be prematurely deenergized due to the opening of contact 53, but that such denergization shall take pla-cconly as a result of'the closing of contact 54 and the consequent slow release due to the inductive action already described.

If an automatic subscriber desires connection with a manual subscriber and the trunk 67, 68 should be selected by the automatic exchange for completing the connection to the manual exchange, such connection is completed from the proper connector switch by wires 109 and 110 and switches 94:

is cllectdl, relay 2 of the selector shown in Fig. 1 (which selector is adapted to be operated only by impulses sent to the automatic exchange over the trunk 67, 68) known as the cut-off relay, is operated in a. manner well known for the purpose of preventing the improper actuation of this selector after the line thereto has been made a part of a connection incoming at the. manual exchange, since if this selector could be operated at this time such inpoming connection would be broken at switches 9-l and 95. When the connection just described has been, established, the automatic subscriber sends an impulse over the line by any suitable means not shown and operates drop 0". Replying be the signal thus given the operator inserts blu 32 in'the llriswerr. ing jack j associated with the drop d and thus energizes relay r as already described this time the .cord circuit is broken at conswitch 2, thereby opening contact 18 and which closes contact 52 and lights lamps m, a as before described and'also opens con:

' tacts 55 and 56 and th'uscuts ofi' drop dfrom the trunk conductors.- The operator multiple, the ring of the jackj corresponding. to the number of the' desired subscriber, If this line is in use a connect-ion is established by a sleeve 21 belongingto a second cord similar to the one shown, from battery 13 as already described forthe first condition. Thus there is a .difi'erence of potential between the ring tested and the 1 testing; tip 20 of the plug, which results in a current flowing over the following circuit,

the key is being-thrown into its listening position at this time: grounded terminal of 20 battery .13, wire 46, tertiary winding 44 of the operators induction coil, contact 31, contact 26, tip 20, ring 12, common tie to a second ring 12 in contact with sleeve 21 of the plug in contact with such ring, contact 27 of such second cord, winding of relay 1', wire 47, back to battery B. Thus a currentimpulse is induced in the secondary winding 43 connected in circuit with the operators receiver 45, which informs her of the fact that the tested line is busy. At

tact 30 and since relay r is not energized and therefore contact19 is open, the click caused by such current flow is not communicated through the answering end of the plug to the earof-the calling subscriber. 1f the line tested is not busy, no click is produced since the only connection to the rings of the line for such a condition is through the energizing winding of relay 1" directly to the grounded terminal of battery B. If the line is not busy the operator inserts the plug 79 in the jack 9' of her multiple corresponding to the number of the subscriber desired, which energizes relay 1' in a manner already described, thus closing contact 19 and permitting the armature of relay 1 to drop, thus closing contact 18 and lighting lamp (1 The operator then throws her key In to its ringing position, which opens contacts 26 and 27 thereby opening the lcord circuit and-closing contacts 24 and 25, thus connecting generator 9 with the tip and sleeve 20 and 21 and thus through springs 10 and 11 with line conductors 8 and 9 respectively, by which generator current is conducted through the ringer 6 and condenser 7 and thereby a signal is given to the substation whereby the subscriber. is called and removes the receiver 5 from hook extinguishing lamp a ,which was lighted 1 whenplug p was inserted inthe jack j, F or this condition the talking circuit is as 55 already described andthe operation of the 'lector switch sc'riber is diagrammatically shown and when the manual subscriber is the calling subscriber, the connection established between the manual exchange and the called subscriber 93 is as follows: winding 6 of the repeating coil, condenser 33, winding 6 sleeve 23, spring 50,- conductor68, first selector switch 90, conductor 97, second se- 91, connector switch 92, through first selector switch 100 to sub scriber 93, thence back through first selector switch 100, connector switch. 92, second selector switch ,91, conductor 96,. to and through first selector switch 90, conductor 67, spring 49, tip 22, back to winding 71 of the repeating coil. hen the automatic subscriber is the calling subscriber, this, connection is established as follows: from sub- I scriber 93, through first selector switch 100,

second selector switch 101, connector switch selector switch 101, first selector switch 100,

back to subscriber 93. The circuit from the manual subscriber to the manual exchange is the same for both cases as already described for Fig. 1.

In Figs. 3 and 4 means are shown for securing a shorter-or longer time interval respectively of operation of the release magnet 1" than that shown in Fig. 1.

Referring to Fig. 3, when plug p is inserted in jack 7' contact 51 is closed and contacts 77, 78 and 79 are opened. As

a result of the closing of contact 51, relay 1'? is energized by the following circuit: grounded terminal of battery B, wire 81, contact 51, winding of relay 1",

resistance 71., back to battery B. As a result of the energization'of relay 7-, contacts 53, 80 and 84' are closed without, however, further operating the apparatus. At the close of the conversation when the plug 72 is .removed frontthe jack 7' contact 51 is broken and contacts 77, 78 and v7 9 are closed.

The closing of contacts 77 and 78 connects conductors 67 and 68 respectively through contacts 80 and 84 by wire 83 to ground G.

The closing of contact 79 establishes an externalelectrical path-of low resistance be- ;tween the terminals of the energizing wind' ing of relay 7' which operates to denergize' this relay in the manner already described, as a result of which after the inductive effect has ceased, contacts 53, and 84 are opened and the connections of conductors 67 and 68 to each other and to ground G are broken. The closing of contact 53 by the energization of relay 7' is for the purpose of maintaining the'energizing circuit of such relay through wire 82 when contact 51 is opened in order to prevent the premature deenergization of such relay due to open circuiting its energizing winding. Thus an arrangement is provided in which the interval of grounding of the conductors 67 and 68 is represented by the length of time required for a single relay to be, deenergized.

In Fig. 4 a-modificatiou of the invention is shown involving-a longer interval of grounding of conductors (37 and 68'than that provided for by the apparatus shown in Fig. 1. In this modification, when plug p is inserted in jack 7' contact 51 is closed, establishing the following circuit: grounded terminal of battery B, wire at), contact- 51,

winding of relay 1, resistance a, wire 4C7, back to battery ll. Thus relay 7" is energized, contact 53 is closed and contact 54 is broken. Then the plug 7) is removed from the jack j at the close of the conversation, contact 5] is opened, but the relay 1' is not deiinergized-since a second energizing path is established as follows: grounded terminal of battery I3, contact 85, winding of relay 7', contact 53, winding of relay 7r, resistance 11}, wire 47, back to battery B. Thus relay 1 is maintained energized and relay 9' is also energized, the operation of the latter brcakingmontact which causes the energization of relay 7- by the following circuit: grounded terminal of battery B, winding of relay r wire 86,

tery B. The energization of relay 1* closes contacts 57, 58, 59 and GO'with the following results' The closing of contacts 5.) and 60 connects conductors 67 and (38 together and to ground G, through wires 70 and 69. The closing of contact 58 establishes an external electrical path of low resistance between the terminals of the winding of relay 1-, thereby causing its decnergization in the manner already described in the other modifications, as a result of which, contact 53 is broken and contact 54: is closed. The closing of contact 54 establishes through wire 88, an external electrical path of low resistance between the terminals of the wind-- ing of relay 1*, thereby causing its deenergization and the closing of contact 85,

ductors to ground G. The opening of con tact 5S and closing of contacts 54 and 85 restores the apparatus to its normal initial condition. Contact 57 is provided for maintaining a closure of the energizing circuit of relays 1' and 1' during the interval of opening of contact 53 so that such relays will not be prematurely denergized but will only be dcii-nergized as a result of the slow action due to the external paths es tablished between the: terminals of the windings of such relays already described. In the modification shown in Fig. 4 it will be noticed a time interval of grounding of con ductors. G7 and G8 is provided which is equal to the time required for three relays to be successively deenergized. Thus it will be seen that means are provided for securing any length of grounding of the trunk conductors 6'7 and (58 as desired, since any number of relays may be used in a series as indicated in Fig. 4, and that the interval thus secured is under any condition a maximum possible without introducing mechania cal resistances or other undesirable elements to prolong this interval. It is obvious that the external clcctricalpath's used, to retard the det nergization of the several relays may It will be understood thatwhilei I have shown my invention in use in connection with a trunk circuit for the purposeindicated in the above description, I do not limit myself to this modification, but claim this invention broadly as a means'for efiecting by a single operation the closure and subsequent opening of an electric circuit and for maintaining such closure for a maximum in terval with a minimum amount of electrical apparatus involved.

\Vhat I claim it:

1. In a telephone system, a manual exchange, an automatic exchange, a source of electric energy. an electrical connection between such exchanges, means for grounding such connection and electro-magnetic mechanism adapted to be energized from such naturalrate of deenergization of such mech anism maybe modified.

2. In a telephone system, a manual ex- 5 change, an automatic exchange, a source of electric energy, an electrical connection between such exchanges, means for grounding such connection and electro-magnetic mechanism associated with such manual exchange and adapted to be energized from such source of electric energy, the deenergization of said electro-magnetic mechanism being under the control of such manual exchange iand being adapted to limit the duration of nism from such manual exchange, means for grounding such connection, electro-magnetic mechanism at the manual exchange and means for limiting the duration of such grounded condition consist ng-in the deenergization of the latter electro-magnetic mechanism said mechanism being adapted to be energized from such source of electric energy, such .deenergization resulting from closing an external electrical path between I the terminals of an energizing winding of such latter mechanism whereby the natural .rate of deenergization of such latter mechanism is modified and the mechanism'at such automatic exchange previously actuated may be restored to its normal condition.

- 4. In a telephone system, a manual exchange, an automatic exchange, a source of electric energy, an electrical connection between suchexchanges, electro-magnetic mechanism at such au'tpmatic exchange, means for actuating suchmechanism from such manual exchange, electro-magne'tic mechanism .at the manual exchange and means whereby the severingof such connection between such exchanges operates to close an external electrical path between the terminals of an energizing winding of the latter electro-magnetic. mechanism which is normally energized from such source of electric energy when such connection is established, such path'operating to deenergize the mechanism at such manual exchange whereby the mechanism at such automatic exchange previously actuated may be restored to its normal condition' 5. In a telephone system, a manual-exchange, an automatic exchange, an electrical connection between such exchanges, a source of'electric energy at such manual exchange,

,electro-magnetic mechanism at such manual' exchange'fadapted to be energized from'such source of electric energy, a second source of electric energy at such automatic exchange, electro-magnetic mechanism at such automatic exchange in circuit with such electrical connection and such source of electric energy at such automatic exchange and adapted to be operated therefrom and means for closing a circuit between such connection and the other terminal of such last mentioned source of electric energy consisting in .the deenergization of the electro-magnetic mechanism at such manual exchange result ing from closing an external electrical path between the terminals of an energizing winding of such last mentioned electro n i'ag m a so netic mechanism. 1

6. In a telephone system, a manual exchange, an automatic exchange, an electrical connection between such exchanges, a source of electric energy at such manual exchange, electro-magnetic mechanism at such manual exchange adapted to be energized from such source of electric energy, a second source of electric energy at such automatic exchange, electro-magnetic mechanism at such auto matic exchange in circuit with such electrical connection and such source of electric energy at such automatic exchange and adapted to be operated therefrom and means for closing a circuit between such connecticn and the other terminal of such last mentioned source of electric energy consisting in two eleetro-magnetic devices, 'the first of which is adapted to close an external electricalxpath between the terminals of an energizing winding of the second and thereby deenergize such second device, which deenergization is' adapted to close an external electrical path between the terminals of an energizing winding of the first and thereby deenergize such first device, whereby the previously actuated electro-magnetic mechanism at such automatic exchange may be restored to its normal condition.

7. In a telephone system, a manual exchange, an automatic exchange, a source of electric energy, an electrical connection between such exchanges, means for grounding such connection, electro-magnetic mech-.

anism adapted, tobe energized from such source of electric energy and adapted by its.

deenergization go limitthe duration of such groundedcon it-ion, such deenergization resulting from short circuiting the'termimale ofan' energizing winding of such mechanism whereby the natural rate of deenergization of such mecha'nism"may be modified. r 8. In a telephone system, a manual exchange, an automatic exchange, a source of electric energy, an electrical connection between such exchanges, means for grounding such connection and electromagnetic mechanism associated with such manualjexchange and adapted to beenergized from such source of electrice'nerg'y, the deenergi- I change, an automatic exchange, a source of zation of said electro-magnetic mechanism being under the control of such manual ex-' change and being adapted to limit the duration of such grounded condition, such deenergization resulting from shortcircuiting the terminals of an energizing winding of such mechanism whereby the natural rate of deenergization of such mechanism may be modified.

9. Ina telephone system, a manual exchange, an automatic exchange, a source of electric energy, an electrical connection between such exchanges, electro-magnetic mechanism at the automatic exchange, means for actuating said electro-magnetic mechanism from such manual exchange, meansforgrounding such connection,- electromagnetic mechanism at such manual exchange adapted by its deenergization to limit the duration of such grounded condition said' mechanism being adapted to be energized from such source of electric energy, such deenergization resulting from short circuiting the terminals of an energizing winding of such latter mechanism whereby the natural rate of denergization of such latter mechanism is modified and the mechanism at such automatic exchange previously actuated may be restored to its normal condition.

10. In a telephone system, a manual exclectric energy, an electrical connection between such exchanges, electro-magnetic mechanism at such automatic exchange, means for actuating such mechanism from such manual exchange, electro-magnetic mechanism at the manual exchange and means whereby the severing of such connection between such exchanges operates to short circuit the terminals of an energizing winding of the latter electro-magnetic mechanism which is normally energized from such source of electric energy when such connection is established, such short circuit operating to de'elnergize the mechanism at such manual exchange whereby the mechanism at .such automatic exchange previously actuated may berestored to its normal condition. I

11. In a telephone system, a manual exchange, an automatic exchange, an electrical connection between such exchanges, a source of electric energy at such manual exchange,

electromagnetic mechanism at such manual exchange adapted to be energized from such sourceof electric energy, a second source of electric energy at'such automatic exchange, electromagnetic mechanism at such automatic exchange in circuit with such electrical connection and such source of electric energy at such automatic exchange and adapted to be operated therefrom and means for closinga circuit between such connection and the other terminal of such last mentioned source of electric energy consisting in ing'from short circuiting the terminals of an energizing winding of such last mentioned electro-magnetic mechanism.

12. In a telephone system, a manual exchange, an automatic exchange, an electrical connection between such exchanges, a source of electric energy at such manual exchange, electro-magnetic mechanism at such manual exchange adapted to be energized from such source of electric energy, a second source of electric energy at such automatic exchange, electro-magnetic mechanism at such automatic exchange in circuit with such electrical connection and such source of electric energy at such automatic exchange and adapted to be operated therefrom and means for closing a circuit between such connection and the other terminal of such last mentioned source of electric energy consisting in two electromagnetic devices, the first of which is adapted to short circuit the ter minals of an energizing winding of the second and thereby deenergize such second device, which denergization is adapted to short circuit the terminals of an energizing winding of the first and thereby denergizc 'such first device, whereby the previously 'ac tuated electro-magnetic mechanism at such automatic exchange may be restored to its normal condition.

13. In a telephone system, a manual exchange, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy, electro-magnetic mechanism at such automatic exchange for operating such exchange, means at such manual exchange for sending impulses from such source of electric .energy over such trunk line adapted to operate the mechanism at such automatic exchange to connect such trunk line with the desired subscribers line terminating at such automatic exchange, electro-magnetic mechanism at the manual exchange and means operated by taking down such trunk line connection for automatically energizing and'deenergizing said electro magnetic mechanism at such manual exchange whereby the trunk line at the manual exchange end is connected to and then disconnected from one terminal of such hhange for sending impulses from such source of electric energy over such trunk line adapted to. operate the mechanism at such automatic exchange to connect such trunk line with the desired subscribers line'termiizs nating at such automatic exchange, electromagnetic mechanism at the manual ex-- change and means operated by taking down such trunk line connect1on for automatically energizing and deenergizing said electromagnetic mechanism at the manual exchange whereby the manual exchange end of the trunk line is connected to and then disconnected from one terminal of such source of electric energy at such automatic exchange,

'electro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such source of electric energy, keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired, a source of electric energy at such manual exchange, electromagnetic devices in circuit with such second source of electric energy adapted to be automatically energized and deenergized when connection with such trunk line is taken down whereby such trunk line conductors are simultaneously connected to and then disconnected from the other terminal of such first source of electric energy.

1.6. In a telephone system, a manual exchange, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electromagnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such sourceof electric energy, keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired, a source of electric energy at such manual exchange, electromagnetic devices in'circuit with such second source of electric energy adapted to be auto matically energized and deenergized when connection with such trunk line is taken down whereby such trunk line conductors are simultaneously connected to and then disconnected from the other terminal of such first source of electric energy and the devices in circuit therewith at such automatic exchange are operated to restore the-mechanism at such automatic exchange to i'ts normal condition.

17. In a telephone system, a manual exchange, an automatic exchange, a. trunk line for connecting such exchanges, a' source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such source of electric energy, keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired, a second source (if electric energy, an electro-magnetic device adapted to be energized from such second source of electric energy, means for connect ing a subscribers line terminating at such. manual exchange with such trunk line and means whereby the disconnect-ion of such connecting means from such trunk line onergizes such last mentioned device and subsequently deenergizes the same by closing an external electrical path between the'term'inals of an energizing winding of such device, such energization and deenergization serving to respectively connect the'trunk line conductors to and disconnect the same 7 from the other terminal of such first source of electric energy and to maintain such connection for a sutficient interval to operate the electro-magnetic devices at such auto matic exchange whereby the mechanism of such automatic exchange is restored to its normal condition, y

18. In a telephone system, a manual ex-' change, an automatic exchange, a trunk 'line for connecting such exchanges, a source of electric energy at such automatic exchange, elect-ro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such source of electric energy, keys at such mariual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electromagnetic devices may be operated as desired, a second source of electric energy, electro-magnetic devices adapted to be energized from such second source of electric energy, means for connecting a subscribers line terminating at such manual exchange with such trunk line and means whereby the disconnection of such connecting means from such trunk line energizes such last mentioned devicesfand subsequently deenergizesthe same by closing external electrical paths between the terminals of energizing windings of such devices, such energization and deener ization serving to respectively connect the'trunk line conductors to and disconnect the same from the other-terminal otsuch first mentioned source of electric energy and to maintain such connection for a sufficient interval to operate the electro-magnetic devices at such automatic exchange whereby the mechanism of such automatic exchange is restored to its normal condition.

19. In a telephone system, a manual ex change, an automatic exchange, atrunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of-such source of electric energy, keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired. a source of electric energy at such manual exchange, a series of electro-magnetic devices adapted to be energized from such'second source of elec tric energy, means for connecting a subscribers linev terminating at such manual exchange with such trunk line and means whereby the disconnection of such connecting means from such trunk line successively energizes such devices at such manual exchange and subsequently deenergizes the same in the same order by closing external electrical paths between the terminals of energizing windings of such devices, the energization and denergization of the last-device of such series serving to respectively connect the trunk line conductors to and disconnect the same from the other terminal of such first mentioned source of electric energy, the interval of such connection being determined by the number of devices in such series. t

20. In a telephone system, a manual ex; change, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such trunk line conductors to the other terminal of such source of electric energy whereby either of such'electro-magnetic devices may be operated as desired, a source of electric energy at such manual exchange, a series of electromagnetic devices adaptedto be energized from such second source of electric energy, means for connecting a subscribers line terminating at such manual exchange with such trunk line, means for automatically energizing the first device of such series when such subscriberfs line is thus connected with such trunk line, means whereby the disconnection of such connecting means from such trunk line establishes a second energizing path for such first device whereby a second one of such series is energized, which in turn energizes the next one of such series and so on each one of such se'riesbeing energized by the operation of the one the terminals of an energizing winding of such first device, which in turn similarly deenergizes the second one of such series and so on, each one of such series being deenergized in this manner by the denergiza for connecting such exchanges, a source of electric energy at such automatic exchange, electromagnetic devices at such automatic exchange connected bet-ween the conductors of such trunk line and one terminal of such source of electric energy, keys at such manual exchange for connecting either of such trunk lineconductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired, a second source of electric energy, an electro-magnetic device adapted tobe energized from such second source of electric energy, means for \connecting a subscribers line terminating at such manual exchange with such trunk line and means whereby the disconnection of such connecting means from such trunk line energizes such last mentioned device and subsequently decnergizes the same by short-cin cuiting the terminals of an energizing winding of such device, such energization and deenergization serving to respectively connect the trunk line conductors to and dis'con-. nect the same from the other terminal of such first source of electric energy and to maintain such connection for a sufiicient interval to operate the electro-magnetic dc vices at such automatic exchange whereby the mechanism of such automatic exchange is restored to its normal condition.

22. In a telephone system, a manual exchange, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connected'bet-ween the conductorsof such trunk line and one terminal of such source of electric energy, keys atsuch manual exchange for; connecting either of such means whereby the disconnection of such connecting means from such trunk line energizes such last mentioned devices and subsequently decnergi zes the same by shortcircuiting the terminals of energizing winddecnergization serving to 'respective-ly'coir meet the trunk line conductors to and disconnect the same from the other terminal or such first mentioned source of electric energy and to maintain such connection for a suflicient interval to operate the electromagnetic devices at such automatic exchange whereby the mechanism of such automatic exchange is restored to, its normal condition.

. 23. In a telephone system a manual exchange, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connected between the conductors of such trunk line and one terminal of such source of electric energ ,keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either-of such electromagnetic devices maybe oper ated as desired, a source of electric energy at such vmanual exchange, a series of electromagnetic devices adapted to be et'lergizcd from such second source ofielectrie energy, means for connecting a subscribers lineterminating at such manual exchange with such trunk line and means whereby the disconnection of such connecting means from such trunk line successively energizes such devices at such ,manual exchange and subsequently-successively denergizes the same in the same order byishort circuiting the termlnals of energizing windlngs of such"- devices, the energization and deenergization of the last device of such series serving torespectively-connect the trunk line conductors to and disconnect the same from the other terminal of such first mentioned source of electric energy, the interval of such connection being determined by the number of devices in such series.

24. In a telephone system, a manual exings of such devices, such energization and change, an automatic exchange, a trunk line for connecting such exchanges, a source of electric energy at such automatic exchange, electro-magnetic devices at such automatic exchange connectedbetween the conductors of such trunk line and one terminal of such source of electric energy, keys at such manual exchange for connecting either of such trunk line conductors to the other terminal of such source of electric energy whereby either of such electro-magnetic devices may be operated as desired, a source of electric energy at such manual exchange, a series of electro-magnetic devices adapted to be energized from such second source of electric energy, means for connecting a subscribers line terminating at such manual exchange wlth such trunk hue, means for automatically energizing the first device of such series when such subscribers line is thus connected with such trunk ,line, means whereby the disconnection of such connecting means from such trunk line establishes a second energizing path for such first device whereby the second one of such series is energized, which in turn energizes the next one of such series and so on each one of such series being energized by the operation of the one preceding it and means whereby the energ'ization of the last device of such series de-..

connect the trunk line conductors to and,

disconnect the same from the other terminal of such first mentioned source of electric energy, the interval of suchconnection beingdetermined by' the number of devices 111 such series. 7 I

- ARTHUR R. KAHL. Witnesses:

CHARLES E. HAGUE, OsoAR M; LEIGH. 

